SUPRAmolecular MATerials for new functional StructurES
Final Report Abstract
The CRP SUPRAMATES endeavor was truly novel and original. It has been focused on unraveling the architecture vs. function relationship in supramolecular materials in particular for applications in organic electronics. The activity within the three years of the CRP was addressed towards different directions which involved the design and synthesis of molecular modules in view of the targeted physico-chemical property, and ultimately towards the device to be fabricated. We have focused our attention on a very large set of either polymeric or oligomeric p-type and n-type semiconductors (including rod-like and disc-like systems). To obtain a detail understanding and ability to pre-program the molecular modules in view of the expected self-assembly behavior and (opto-)electronic property, we have changed systematically the size of the molecules as well as the regio-specific substitution, also to improve the processability in thin films. In this regard, we have paid a particular attention to the development of new processing and post processing procedures including zone-casting, soft-landing, dip-coating, spray-deposition, snom assisted lithography, (temperature-enhanced) solvent vapor annealing etc. to control the molecular assembly across multiple length scales, from the sub-nanometers scale up to the macroscopic scale. The complementary expertise and facilities available in the six nodes of SUPRAMATES made it possible to investigate a variety of physico-chemical properties making use of state-of-the-art approaches such as time-resolved optical characterizations, AFM, STM, KPFM, C-AFM, electro-absorption to name a few. The emphasis in terms of devices fabrication and optimization was on field-effect transistors and solar cells in particular. It was demonstrated that a supramolecular approach over the film formation is key to obtain enhanced characteristics in devices. The most innovative research carried out within SUPRAMATES involved all the six nodes. It was devoted to the careful and pre-programmed control over the inter-chromophore interactions making use of macromolecular scaffolds based on ultra-rigid poly-isocyanide polymers exposing optically and/or electrically active moieties in the peripheral positions. Such a multi-chomophoric array was synthesized in different derivatives each exposing a well-defined functional group such as perylene dyes, carbazoles and porphyrins. The research on this new class of systems was focused on 1) the single-molecule study of the reputation of individual polymers embedded in a viscous optically inert polymer matrix, 2) the fabrication of field-effect transistors both using as electroactive layer mono-component and bi-component films, and 3) the realization of solar cell prototypes and thorough nanoscale resolved exploration of the photovoltaic activity in bi-component films. Such a unique macromolecular scaffolding approach is of general importance as it can be exploited to control the position of whatever functional unit for applications not only in (opto-)electronics and photonics, but also in bio-medicine, catalysis, etc.
